EP0290136A2

EP0290136A2 - 7-Beta-substituted-3-lower alkanoylacetoxymethyl-7-alpha-methoxy-3-cephem-4-carboxylic acid and process for production of same

Info

Publication number: EP0290136A2
Application number: EP88302955A
Authority: EP
Inventors: Masami Abe; Hideo Eiki
Original assignee: Yamanouchi Pharmaceutical Co Ltd
Current assignee: Yamanouchi Pharmaceutical Co Ltd
Priority date: 1987-03-31
Filing date: 1988-03-31
Publication date: 1988-11-09
Also published as: EP0290136A3; US4908443A

Abstract

7β-substituted-3-lower alkanoylacetoxymethyl-7α-methoxy-3-cephem-4-carboxylic acid of formula (I) and salts thereof : (wherein R¹ represents a lower alkyl group and R² represents an amino group which may be protected) are useful intermediates for preparing anti-bacterial cephamycin compounds.

Description

The present invention relates to intermediate compounds for synthesizing cephamycin compounds useful as antibacterial agents and to a process for production of the same. More particularly, the present invention provides 7β-substituted-3-lower alkanoylacetoxymethyl-7α-methoxy-3-cephem-4-carboxylic acid (I) and salts thereof :
wherein R¹ is a lower alkyl (e.g.C₁-C₄) group and R² an amino group which may be protected.
The present invention also provides a process for producing these compounds which comprises culturing bacteria which belong to the genus Streptomyces and are capable of producing cephamycin compound (II) :
wherein R³ is a hydrogen atom or a methoxy group and R⁴ a hydroxy or sulfoxy group; allowing yeast belonging to the genus Torulopsis, or esterase derivable from the yeast or material containing this esterase to act on the accumulated cephamycin compound (II) in the culture solution to form 7β-(D-5-amino-5-carboxyvaleramido)-3-hydroxymethyl-7α-methoxy-3-cephem-4-carboxylic (oganomycin E) (III) :
or salt thereof (fermentation production step); reacting this oganomycin compound (optionally with its amino group protected), with lower alkanoylacetic acid or reactive derivative thereof (chemical process step); and optionally removing a protective group and/or converting to or from salt form.
The compounds according to this invention are novel and there is no published report on them.
A characteristic feature of their chemical structure is the lower alkanoylacetoxymethyl group at the 3-position of the cephalosporin ring. The compounds of the present invention can easily be prepared employing as an intermediate compound oganomycin E which can be produced in high yield by our novel fermentation and hydrolysis process.
Known methods for producing oganomycin E by fermentation include culturing Streptomyces chartreusis SF-1623 under aerobic conditions and harvesting the compound from the culture solution (JP-A-121488/1975) and culturing Streptomyces oganonensis and harvesting the compound from the culture solution (JP-A-43697/1982).
However, the former method gives a low yield and is unsuitable for industrial production. The latter method provides at least 1000 times the yield but the concentration of organomycin E accumulated in the culture solution is approximately 5mg/ml.
As a result of extensive investigation to achieve a higher product concentration, we have found that by incorporating yeasts belonging to the genus Torulopsis in some fermentation media and culturing them, accumulated quantities of oganomycin E can be enhanced.
Known methods for producing oganomycin E may include not only culturing oganomycin E-producing bacteria and harvesting directly oganomycin E accumulated in the culture solution, but also producing analogous cephamycin compound (II) and hydrolysing the ester of the cephamycin compound to form oganomycin E.
We have found that yeasts belonging to the genus Torulopsis and esterase derivable therefrom can easily hydrolyse the ester at the 3-position of cephamycin compounds (II) to efficiently convert to oganomycin E. The compounds according to the present invention can then be produced by chemically treating the oganomycin E efficiently prepared by this fermentation method.
The fermentation production and chemical process step of the present invention are discussed separately and in greater detail below.

1. Fermentation Production Step

This step includes culturing cephamycin compound (II)-producing bacteria and allowing yeast belonging to the genus Torulopsis or esterase derivable therefrom or material containing the esterase to act on accumulated cephamycin compounds in the culture solution to form oganomycin E. Examples of bacteria capable of producing cephamycin compounds (II) which can be used in the present invention include Streptomyces griceus MA-2837 and MA-4125a (JP-A-3286/1971)Streptomyces viridochromogenes, Streptomyces fimbriatus, Streptomyces halstedii, Streptomyces rochei, Streptomyces cinnamonensis and Streptomyces chartreusis (Belgian patent 764,160). Further, Streptomyces oganonensis Y-G19Z by-produces cephamycin compounds (II) and thus can also be used (JP-A-79394/1980).
The cephamycin compounds (II) produced by these micro-organisms are specifically cephamycin A (R³= -OCH₃, R⁴= -OSO₃H), cephamycin B (R³= -OCH₃, R⁴= -OH), oganomycin A (R³= -H, R⁴= -OSO₃H), oganomycin B (R³= -H, R⁴= -OH), etc.
The esterase derivable from yeasts belonging to the genus Torulopsis which can be employed in the present fermentation production step is an enzyme capable of hydrolysing the ester bond at the 3-side chain of said cephamycin compounds (II). Material containing the aforementioned esterase may be in any form and examples are micro-organisms carrying the esterase, immobilized esterase, etc.
As a result of investigation on various micro-organisms isolated from the soil, we have found that the aforementioned esterase which can hydrolyse the 3-side chain ester of cephamycin compounds (II) is present in a genus of yeast. One suitable yeast strain had various properties as follows:

(1) Morphological Properties:

Vegetative cells are spherical or oval, sometimes protractile in various media. The size is 3.0 to 10 µm× 2.0 to 5 µm with oval cells and 3 to 11 µm with spherical ones.
Vegetative propagation occurs by multipolar budding. Formations of Pseudomycelia, chlamydospore, oidispore, budding spore, etc. are absent but a trace of pseudomycelia-like formation sometimes occurs. Neither ascospores nor balistospores are formed.

(2) Culturing Properties (cultured at 25°C for 3 to 14 days)

[1] Maltose Medium

The medium is somewhat turbid as a whole and colored pale pink to light orange. Neither skin nor precipitate is formed. Generation of gas is not observed.

[2] Potato Dextrose Agar

Colonies are smooth, glossy, colored pale orange to light orange and rise to a hemispherical shape on agar. No diffusible dye is noted.

(3) Physiological Properties

[1] Fermentation of glucose is weak but positive. Fermentation of fructose, galactose, sucrose, maltose and raffinose is negative.
[2] Utilization of Carbon Source (cultured at 25°C for 21 days)
Maltose-
D-Galactose +
Fructose-
Glucose +
L-Arabinose +
D-Xylose +
Sucrose -
Inositol -
L-Ramnose-
L-Raffinose -
Mannitol -
Lactose +
D-Sorbitol -
Salicine +
Glycerine +
+ : utilized
- : not utilized
[3] Assimilation of Nitrates: Positive
[4] Formation of Starch-like Substance: Negative
[5] Formation of Carotinoid Dye:
Negative(bacterial dye is a non-carotinoidal substance insoluble in acetone and petroleum ether)
[6] Formation of Ester: Negative
[7] Acid-formation: Negative
[8] Decomposition of Oils and Fat: Negative
[9] Vitamin Auxotrophy: None
[10] Growth Temperature:
It grows at 10 to 33° C but not at 5 and 37°C.
[11] Urease: Positive

In summary, this strain belongs to a non-spored yeast; nutrient cells are spherical or oval; and pseudo-mycelia are sometimes observed as traces; no starch-like substance is formed but assimilation of nitrates is positive; neither skin nor precipitate is formed by liquid culture; colonies are colored pale orange to light orange but this dye is not of carotinoid; further fermentation of glucose is weak but positive. Upon examination of the literature, genera of microorganisms having these properties are the genus Cryptococcus and the genus Torulopsis which are characterized as non-spored yeast, forming intracellular non-carotinoid dye, propagating in spheral or oval multipolar buds and neither forming oidispore nor pseudomycelia. The former is covered with a capsule, colonies are viscous and starch-like substance is formed; the present strain does not show such properties and hence is distinguishable. On the other hand, the morphological properties, physiological properties,etc. of the present strain correspond closely with those of yeasts belonging to the genus Torulopsis. The new strain has been named the type strain Torulopsis sp. YE-0807L accordingly. The type strain has been deposited in the Agency of Industrial Science and Technology, the Fermentation Research Institute under the accession number FERM BP-1158.
In addition to this strain, other yeasts of genus Torulopsis carrying or producing the esterase or treated products thereof can also be employed in the present invention.
For present purposes yeasts are a good group of micro-organisms as compared to, e.g. bacteria and molds, since they do not inhibit the fermentation metabolism system and can achieve optimum conditions. This is particularly important for the mixing culture method in which several microorganisms are co-cultured, e.g. cephamycin compound-producing bacteria are cultured in the presence of esterase-producing micro-organisms to produce oganomycin E. Other esterase-producing microorganisms may have a potent productivity of amylases or proteases, or of acidic substances or basic substances, or may have a large propagation rate or oxygen absorption rate, etc.,so as to disrupt the fermentation metabolism environment and hence reduce the total product yield of oganomycin E. Accordingly, such other micro-organisms are not suitable for the present invention.
According to the present invention, oganomycin E can be prepared as follows:

Process 1 (mixing fermentation method)

In the mixing fermentation method, a cephamycin compound-producing strain is cultured under conditions for the production of the cephamycin compounds by fermentation and yeast belonging to the genus Torulopsis is inoculated and both strains are simultaneously cultured. Deep culture using liquid medium is advantageous.
The mixing fermentation method is described in more detail below.
The medium used for the mixing culture may be any medium containing nutrient sources that the cephamycin compound-producing bacteria belonging to the genus Streptomyces can utilize. Thus a synthetic medium, semi-synthetic medium or natural medium can be used. In such a medium, glucose, sucrose, mannitol, glycerine, dextrin, starch, vegetable oils, etc. are used as carbon sources and meat extract, peptone, gluten meal, cotton seed lees, soybean powders, peanut powders, fish powders, corn steep liquor, dry yeast, yeast extract, ammonium sulfate, ammonium nitrate, urea and other organic or inorganic nitrogen sources are employed as nitrogen sources. Further metal salts, e.g. sulfates, nitrates, chlorides, carbonates, phosphates, etc. of Na, K, Mg, Ca, Zn, Fe, etc. may be incorporated, if necessary or desired. In particular, the incorporation of magnesium carbonate is effective for increasing the productivity (titer) of oganomycin E. Antibiotic production-accelerating substances or defoaming agents such as methionine, cysteine, cystine, methyl oleate, lard oil, silicone oil, surfactants, etc. may be used if necessary or desired.
It is generally advantageous to culture under aerobic conditions. It is desired that the culturing temperature is in a range of about 18 to about 35° C, preferably about 30° C. Good results are obtained when the pH of the medium is kept in a range of about 5 to about 10, preferably about 6 to about 8. The period for incubation varies depending upon composition of the medium, temperature, etc. but is generally about 3 to about 10 days. Inoculation of the yeast belonging to the genus Torulopsis producing the esterase at an initial stage of the culture is effective; good results may be obtained when inoculation is at the time of initiating the culture or up to the second day. When using the esterase or material containing the same instead of the yeast, it may be aseptically incorporated prior to the production of the cephamycin compound (II); alternatively, the culture solution containing the cephamycin compound (II) may be cycled to a reactor containing the esterase.

Process 2 (enzymatic hydrolysis of cephamycin compounds)

This process comprises using cephamycin compound (II) as a substrate, and allowing yeast belonging to the genus Torulopsis, or esterase obtainable therefrom or material carrying it, to act thereon to produce oganomycin E. The yeast,or the esterase or material carrying it, can be mixed with a solution of the cephamycin compound (II),the mixture shaken at about 30° C at neutral pH,and the formed oganomycin E separated. As the solution of cephamycin compound (II), there may be used a fermentation solution containing compound (II), a fermentation filtrate, or a solution of cephamycin compound (II) separated and isolated. As the esterase source, there can be utilized a culture solution per se of yeast belonging to the genus Torulopsis, cells of the yeast, ground cells, an extract of the esterase active fraction, or solid carriers (activated charcoal, diatomaceous earth, hydrophilic gel, high mol.wt. resins, etc.) having immobilized thereon esterase or yeast carrying the same.
To isolate and harvest oganomycin E from the culture, there may be adopted conventional methods for isolating antibiotics from the culture of micro-organisms. Oganomycin E is mainly contained in the culture solution and therefore micro-organism cells can be removed by centrifugation or filtration and thereafter oganomycin E extracted from the filtrate. Oganomycin E can be separated, harvested and purified as for production of ordinary antibiotics utilizing difference in solubilizing property or solubility in an appropriate solvent, difference in precipitating property or precipitating rate from a solution, difference in adsorptive affinity to various adsorbants, difference in distribution between two liquid phases, etc.
These isolating methods can be applied singly, in any combination in any order, or repeatedly, if necessary or desired.
In the process of the present invention, oganomycin E may be obtained as a free acid or a salt such as an alkali metal salt (e.g., Li-, Na-, K-salts),alkaline earth metal salt (e.g., Ca-, Mg-, Ba-salts), an organic amine salt (e.g., triethylamine salt), etc.

2. Chemical Process Step

The compounds according to the present invention can be prepared by chemically treating oganomycin E obtained in the aforementioned fermentation production step.
This chemical process step is shown by the following reaction equations:
This process utilizes as raw material, oganomycin E, obtained by the above-described fermentation production step, wherein the α-amino group at the 5-carboxy valeramide group may be protected, if desired; it is performed by reacting oganomycin E with lower alkanoylacetic acid (IV) :

R¹COCH₂COOH (IV)

(wherein R¹ is as defined above) or reactive derivative thereof.
Examples of the protective group for the amino group include aromatic acyl groups such as phthaloyl-, benzoyl-, p-nitrobenzoyl-, toluoyl-, benzenesulfonyl-, phenoxyacetyl groups, etc., N-carbamoyl group formed by reacting with arylisocyanate, etc. The protective group may subsequently be removed.
Examples of lower alkanoylacetic acids (IV) are are straight- or branched chain (C₁-C₅ alkanoyl)acetic acids such as acetoacetic acid, propionylacetic acid, butyrylacetic acid, valerylacetic acid, etc.
Examples of the reactive derivatives of the above alkanoylacetic acids include diketene, lower alkanoylacetic acid halides or acid anhydrides etc.
The reaction of the present process can be performed using lower alkanoylacetic acid (IV) or reactive derivative thereof in equimolar amounts or with slight excess of the raw material compound (III). The reaction temperature is not specifically limited but ice-cooling or heating is preferred. Examples of the reaction solvent are inert solvents to the reaction such as dichloromethane, chloroform, dichloroethane, dimethylformamide, tetrahydrofuran, acetone,etc. To perform the reaction the 4-position carboxylic group may be protected, if necessary or desired, and the protective group may subsequently be removed; alternatively, any amine such as triethylamine, etc. may be added.
The resultant compound (I) of this invention can be isolated as it is or as a salt and purified. Isolation and purification can be effected employing conventional chemical operations such as extraction, crystallization, recrystallization, various kinds of chromatography, etc.
According to the process of the present invention the 3-side chain ester of cephamycin compounds (II) is enzymatically hydrolyzed to efficiently convert to oganomycin E and then the desired compound of this invention is industrially and cheaply produced using the aforesaid oganomycin E as the raw material. In particular, in the mixing fermentation method the cephamycin compound (II) by-produced and accumulated in the culture medium can be converted to oganomycin E without isolation and therefore a culture solution containing oganomycin E alone and at a high concentration can be obtained. The present fermentation production method can give an oganomycin E product concentration 5 times greater than previous conventional methods and the resulting oganomycin E can be employed in the subsequent chemical treating process as the raw material. Thus, the present invention provides an industrially advantageous process.
The compounds according to the present invention are also useful as intermediate compound for producing cephamycin series compounds possessing superior antibacterial activity.
Compounds of formula (I) can be converted to cefotetan exhibiting excellent antibacterial activity according to the process shown by the following reaction equations:
Cefotetan of excellent antibacterial activity can be obtained by using a compound (I) as starting material, substituting the 3-position lower alkanoylacetyloxy group of said compound for a (1-methyltetrazol-5-yl) thio group to give compound (V), removing the 7-position acyl group by hydrolysis to yield compound (VI), and reacting compound (VI) with 4-(carbamoylcarboxymethylene)-1,3-dithietan-2-sulfonic acid.
The present invention is illustrated in more detail by the Examples below. Example (a) relates to production of oganomycin E by a mixing fermentation production step, (b) to production of N-phthaloyloganomycin E and (c) to production of a desired compound of the present invention, respectively.
As a reference example, there is shown the first process step in converting a compound (I) of this invention to cefotetan (VIII).

Example (a)

In a 500 ml Sakaguchi flask 100 ml of seed medium containing 1% starch, 1% glucose, 1.5% soybean powder, 0.5% yeast extract, 0.1% hydrogen disodium phosphate, 0.05% magnesium sulfate and 0.3% sodium chloride was charged, followed by sterilizing at 120° C for 20 minutes. Streptomyces oganensis Y-G19Z was inoculated and cultured at 30° C for 2 days. A 500 ml Erlenmeyer's flask charged with 50 ml of a main fermentation medium containing 18% dextrin, 2% glycerin, 3% soybean powder, 2% gluten meal, 0.2% magnesium carbonate and 0.23% sodium hydroxide was prepared and sterilized at 120° C for 20 minutes 2 ml of the above-described seed culture solution was transplanted,and incubation was initiated at 30° C with a rotary shaker at 240 rpm. Separately, a 500 ml Sakaguchi flask containing 100 ml of GPY medium (1% glucose, 0.25% peptone and 0.25% yeast extract) was sterilized and prepared. Thereafter, esterase-producing yeast Torulopsis sp. YE-0807L (FERM BP-1158) was inoculated, followed by seed culturing at 30°C for 2 days. On the first day of the main fermentation of the Y-G19Z strain, 1 ml each of the seed culture solution of the esterase-producing yeast was added and the incubation was continued for 7 days. Subsequent to the second day of the fermentation, 3 flasks were provided for analysis of the concentration of oganomycin E, etc. daily. The concentration of the product was determined by HPLC (column: LS224 (made by Toyo Soda Co., Ltd., 4 mm×500 mm), eluant: 0.02M citric acid (pH 3.2), detection: UV detector 254 nm).
A linear increase of the concentration of oganomycin E was observed as shown by a mean value of the 3 flasks in Table 1 below. Further the concentration reached 60 mM or more on the 7th day.

Example (b)

To one litre of the fermentation filtrate containing 4327 γ/ml of oganomycin E were gradually added 50 g of N-carboethoxyphthalimide in 300 ml of acetone under stirring at room temperature,and,while adjusting the pH of the mixture between 9.2 and 9.5 with 40% potassium carbonate, the mixture was allowed to stand for 90 minutes.
After the reaction finished, the mixture was adjusted to pH 4.0 with 4N HCl and passed through 1 ℓ of SP 207 resin (Mitsubishi Chemical Industries Ltd). After washing with water, the adsorbed N-phthaloyloganomycin E was eluted with approximately 1 ℓ of 50% acetone-water, the eluate adjusted to a pH not less than 4.0. The eluate was concentrated to approximately 300 ml under reduced pressure and extracted twice with 300 ml of methylethylketone at pH 4.5 to remove impurities. Further, the eluate was adjusted to pH 2.5 under ice-water cooling and extracted twice with 300 ml of methylethylketone to extract the desired compound.
The methylethylketone solution containing N-phthaloyloganomycin E was dried over anhydrous sodium sulfate and the solvent distilled off at 30° C under reduced pressure to give 21 g of dried N-phthaloyloganomycin E having 14% purity.
One g of the dried N-phthaloyloganomycin E thus obtained was dissolved in 2 ml of 50% acetone-water and spotted on a TLC plate (silica gel 60F254; Merck) and developed with a solvent (ethyl acetate : methanol : water = 6:3:1) at 4° C for 2 hours. After developing, the UV spot portion including N-phthaloyloganomycin E was scratched, and to the resulting silica gel was added 20 ml of distilled water to perform elution for 30 minutes under stirring. The eluate was centrifuged and concentrated at 30° C under reduced pressure. Approximately 1 ml of the concentrated solution was subjected to a TLC plate once again as above-mentioned and 2-3 ml of the concentrated solution thus obtained put into a sample bottle and lyophilized to give 40 mg of the lyophilized product. The physico-chemical properties of the thus obtained N-phthaloyloganomycin E are shown below:

(i) Infrared absorption spectrum ν
cm⁻¹
2950, 3000-2400 (carboxylic acid), 1770 (β-lactam), 1710, 1600, 1390

(ii) Mass spectrum (FAB) for C₂₃H₂₃N₃O₁₀S MW 533

m/Z 556 (M⁺ + Na)

(iii) Nuclear magnetic resonance spectrum (in DMSO - d₆ , TMS internal standard)

δ ppm: 1.46 (2H, m), 2.20 (4H, m)
3.34 (3H, s), 4.84 (1H, s)
7.88 (4H, s), 9.00 (1H, s)

Example (c)

After 20 g of the dried residue containing N-phthaloyloganomycin E were dissolved in 5 ml of triethylamine and 40 ml of dichloromethane, to the solution were added under stirring 2 ml of diketene and the mixture was allowed to react for an hour at room temperature. After reaction, the reaction mixture was evaporated to dryness under reduced pressure. To the residue were added 50 ml of distilled water and 50 ml of ethyl acetate; the resulting mixture was shaken at pH 5.5 for 3 minutes and the aqueous layer containing N-phthaloyl-3-acetoacetoxymethyloganomycin E separated. To the layer was again added 50 ml of ethyl acetate and the desired product was extracted at pH 2.0 adjusted with 4N HCl The ethyl acetate layer containing the desired product was dried over anhydrous sodium sulfate, and evaporated to dryness at 30° C under reduced pressure to yield 3.3 g of the dried residue of N-phthaloyl-3-acetoacetoxymethyloganomycin E having 51% purity.
To the dried N-phthaloyl-3-acetoacetoxymethyloganomycin E was added 1 ml of 50% acetone-water and the mixture spotted on a TLC plate (silica gel 60 F254; Merck) and developed with a solvent (ethyl acetate : methanol : water = 6:3:1 ) at 4° C for 2 hours. After developing the UV-spot portion showing the presence of N-phthaloyl-3-acetoacetoxymethyloganomycin E was scratched and to the resulting silica gel was added 20 ml of distilled water to elute for 30 minutes under stirring. The eluate was centrifuged and concentrated at 30° C under reduced pressure. The solution concentrated to approximately 1 ml was spotted on a TLC plate and treated again as described above. 2 - 3 ml of the concentrated solution thus obtained was introduced into a sample bottle and lyophilized to give 70 mg of the product.
The physico-chemical properties of the product are shown below:

(i) Infrared absorption spectrum ν
cm⁻¹
2950, 2900-2700, 1760 (β-lactam), 1705, 1608, 1390

(ii) Mass spectrum (FAB) for C₂₇H₂₇N₃O₁₂S MW 617

m/Z 640 (M⁺ + Na)

(iii) Nuclear magnetic resonance spectrum

δ ppm : 1.44 (2H, m), 2.18 (3H, s), 2.23 (2H, m), 3.34 (3H, s), 2.95, 3.36 (2H, dd), 3.59 (2H, s), 4.40 (1H, m), 4.79, 4.94 (2H, dd), 4.89 (1H, s), 7.85 (4H, s), 9.01 (1H, s)

Reference Example

After dissolving 3 g of the dried residue containing N-phthaloyl-3-acetoacetoxymethyloganomycin E prepared in Example (c) in 20 ml of 0.05M phosphate buffer solution of pH 6.0, to the solution were added 0.12 g of sodium salt of 1-methyl-1,2,3,4-tetrazol-5-thiol · dihydrate and 6 ml of acetone, followed by standing in a water bath at 47°C. By sampling after 5 hours and analyzing quantitatively using, as an authentic standard, N-phthaloyloganomycin G previously identified, production of 1.2 g of N-phthaloyloganomycin G was confirmed.
The solution of 0.5 g of resulting N-phthaloyloganomycin G in 1 ml of 50% acetone-water was spotted on a TLC plate (silica gel 60 F254; Merck) and developed with a solvent (ethyl acetate : methanol : water = 6:3:1) at 4° C for 2 hours. After development, the UV-spot portion showing the presence of N-phthaloyloganomycin G was scratched and the resulting silica gel subjected to elution with 20 ml of distilled water for 30 minutes under stirring. The eluate was centrifuged and concentrated at 30° C under reduced pressure. The solution concentrated to approximately 2-3 ml was introduced into a sample bottle and lyophilized to yield 220 mg of the lyophilized product. The physico-chemical properties of this product are shown below:

(i) Infrared absorption spectrum ν
cm⁻¹
2950, 3000-2500 (carboxylic acid), 1760 (β-lactam), 1710, 1600, 1390

(ii) Mass spectrum (FAB) for C₂₃H₂₅N₇O₉S₂ MW 631

m/Z 654 (M⁺ + Na)

(iii) Nuclear magnetic resonance spectrum (DMSO -d₆ , TMS internal standard)

δ ppm : 1.44 (2H, m), 2.22 (4H, m), 3.36 (3H, s), 3.36 (2H, q), 3.94 (3H, s), 4.0-4.6 (3H, m), 4.88 (1H, s), 7.86 (4H, s), 9.04 (1H, s)

Claims

1. 7β-substituted-3-lower alkanoylacetoxymethyl-7α-methoxy-3-cephem-4-carboxylic acid of formula (I) or a salt thereof :

wherein R¹ represents a lower alkyl group and R² represents an amino group which may be protected.

2. A process for producing 7β-substituted-3-lower alkanoylacetoxymethyl-7α-methoxy-3-cephem-4-carboxylic acid (I) or a salt thereof :

wherein R¹ represents a lower alkyl group and R² represents an amino group which may be protected, which comprises culturing bacteria belonging to the genus Streptomyces and capable of producing cephamycin compound (II) :

wherein R³ represents a hydrogen atom or methoxy group and R⁴ represents a hydroxy or sulfoxy group; allowing yeast belonging to the genus Torulopsis, esterase derivable therefrom or material containing the esterase to act on accumulated cephamycin compound (II) in the culture solution to form 7β-(D-5-amino-5-carboxyvaleramido)-3-hydroxymethyl-7α-methoxy-3-cephem-4-carboxylic (III) :

or a salt thereof; reacting this intermediate, the amino group of which may be protected, with lower alkanoylacetic acid or reactive derivative thereof; and optionally removing a protective group and/or converting to or from salt form.

3. A process according to claim 2 wherein said yeast belonging to the genus Torulopsis is Torulopsis sp. YE - 0807L, or a mutant or derivative thereof.